In this verse, the three colors mentioned-śukla, rakta and kṛṣṇa—are not to be understood literally, in terms of what we experience with our senses, but rather as representatives of sattva-guṇa, rajo-guṇa and tamo-guṇa. After all, sometimes we see that a duck is white, although it is in tamo-guṇa, the mode of ignorance. Illustrating the logic called bakāndha-nyāya, the duck is such a fool that it runs after the testicles of a bull, thinking them to be a hanging fish that can be taken when it drops. Thus the duck is always in darkness. Vyāsadeva, however, the compiler of the Vedic literature, is blackish, but this does not mean that he is in tamo-guṇa; rather, he is in the highest position of sattva-guṇa, beyond the material modes of nature. Sometimes these colors (śukla-raktas tathā pītaḥ) are used to designate the brāhmaṇas, kṣatriyas, vaiśyas and śūdras. Lord Kṣīrodakaśāyī Viṣṇu is celebrated as possessing a blackish color, Lord Śiva is whitish, and Lord Brahmā is reddish, but according to Śrīla Sanātana Gosvāmī in the Vaiṣṇava-toṣaṇī-ṭīkā, this exhibition of colors is not what is referred to here.
The real understanding of śukla, rakta and kṛṣṇa is as follows. The Lord is always transcendental, but for the sake of creation He assumes the color rakta as Lord Brahmā. Again, sometimes the Lord becomes angry. As He says in Bhagavad-gītā (16.19):
tān ahaṁ dviṣataḥ krūrān
saṁsāreṣu narādhamān
kṣipāmy ajasram aśubhān
āsurīṣv eva yoniṣu
"Those who are envious and mischievous, who are the lowest among men, are cast by Me into the ocean of material existence, into various demoniac species of life." To destroy the demons, the Lord becomes angry, and therefore He assumes the form of Lord Śiva. In summary, the Supreme Personality of Godhead is always beyond the material qualities, and we should not be misled into thinking otherwise simply because of sense perception. One must understand the position of the Lord through the authorities, or mahājanas. As stated in Śrīmad-Bhāgavatam (1.3.28), ete cāṁśa-kalāḥ puṁsaḥ kṛṣṇas tu bhagavān svayam.
(Srimad Bhagavatam-----10:3:20-----purport).

The Vaiṣṇava-toṣaṇī remarks that although the handcart was higher than the child, the child could easily touch the wheel of the cart, and this was sufficient to send the demon down to the earth. The Lord simultaneously pushed the demon to the earth and superficially broke the handcart.
(Srimad Bhagavatam-----10:7:7-----purport).

Śrī Śukadeva Gosvāmī continued: One day when mother Yaśodā saw that all the maidservants were engaged in other household affairs, she personally began to churn the yogurt. While churning, she remembered the childish activities of Kṛṣṇa, and in her own way she composed songs and enjoyed singing to herself about all those activities.
Śrīla Viśvanātha Cakravartī Ṭhākura, quoting from the Vaiṣṇava-toṣaṇī of Śrīla Sanātana Gosvāmī, says that the incident of Kṛṣṇa's breaking the pot of yogurt and being bound by mother Yaśodā took place on the Dīpāvalī Day, or Dīpa-mālikā. Even today in India, this festival is generally celebrated very gorgeously in the month of Kārtika by fireworks and lights, especially in Bombay. It is to be understood that among all the cows of Nanda Mahārāja, several of mother Yaśodā's cows ate only grasses so flavorful that the grasses would automatically flavor the milk. Mother Yaśodā wanted to collect the milk from these cows, make it into yogurt and churn it into butter personally, since she thought that this child Kṛṣṇa was going to the houses of neighborhood gopas and gopīs to steal butter because He did not like the milk and yogurt ordinarily prepared.
(Srimad Bhagavatam-----10:9:1-2-----translation and purport).

From the body of the gigantic python, a glaring effulgence came out, illuminating all directions, and stayed individually in the sky until Kṛṣṇa came out from the corpse's mouth. Then, as all the demigods looked on, this effulgence entered into Kṛṣṇa's body.
Apparently the serpent named Aghāsura, because of having received association with Kṛṣṇa, attained mukti by entering Kṛṣṇa's body. Entering the body of Kṛṣṇa is called sāyujya-mukti, but later verses prove that Aghāsura, like Dantavakra and others, received sārūpya-mukti. This has been broadly described by Śrīla Viśvanātha Cakravartī Ṭhākura with references from theVaiṣṇava-toṣaṇī of Śrīla Jīva Gosvāmī. Aghāsura attained sārūpya-mukti, being promoted to the Vaikuṇṭha planets to live with the same four-armed bodily features as Viṣṇu. The explanation of how this is so may be summarized as follows.
The effulgence came out from the python's body and became purified, attaining spiritual śuddha-sattva, freedom from material contamination, because Kṛṣṇa had stayed within the serpent's body, even after the serpent's death. One may doubt that such a demon, full of mischievous activities, could attain the liberation of sārūpya or sāyujya, and one may be astonished about this. But Kṛṣṇa is so kind that in order to drive away such doubts, He had the effulgence, the individual life of the python, wait for some time in its individuality, in the presence of all the demigods.
Kṛṣṇa is the full effulgence, and every living being is part and parcel of that effulgence. As proved here, the effulgence in every living being is individual. For some time, the effulgence remained outside the demon's body, individually, and did not mix with the whole effulgence, the brahmajyoti. The Brahman effulgence is not visible to material eyes, but to prove that every living being is individual, Kṛṣṇa had this individual effulgence stay outside the demon's body for some time, for everyone to see. Then Kṛṣṇa proved that anyone killed by Him attains liberation, whether sāyujya, sārūpya, sāmīpya or whatever.
But the liberation of those who are on the transcendental platform of love and affection is vimukti, special liberation. Thus the serpent first entered the body of Kṛṣṇa personally and mixed with the Brahman effulgence. This merging is called sāyujya-mukti. But from later verses we find that Aghāsura attained sārūpya-mukti. Text 38 explains that Aghāsura attained a body exactly like that of Viṣṇu, and the verse after that also clearly states that he attained a completely spiritual body like that of Nārāyaṇa. Therefore in two or three places the Bhāgavatam has confirmed that Aghāsura attained sārūpya-mukti. One may then argue, How is it that he mixed with the Brahman effulgence? The answer is that as Jaya and Vijaya, after three births, again attained sārūpya-mukti and association with the Lord, Aghāsura received a similar liberation.
(Srimad Bhagavatam-----10:12:33-----translation and purport).

The Śrīvatsa mark is described by the Vaiṣṇava-toṣaṇī as being a curl of fine yellow hair on the upper portion of the right side of Lord Viṣṇu's chest. This mark is not for ordinary devotees. It is a special mark of Viṣṇu or Kṛṣṇa.
(Srimad Bhagavatam-----10:13:47-48-----purport).

Śrī Sanātana Gosvāmī is described in the Gaura-gaṇoddeśa-dīpikā (181). He was formerly known as Rati-mañjarī or sometimes Lavaṅga-mañjarī. In the Bhakti-ratnākara it is stated that his spiritual master, Vidyā-vācaspati, sometimes stayed in the village of Rāmakeli, and Sanātana Gosvāmī studied all the Vedic literatures from him. He was so devoted to his spiritual master that this cannot be described. According to the Vedic system, if someone sees a Muslim he must perform rituals to atone for the meeting. Sanātana Gosvāmī always associated with Muslim kings. Not giving much attention to the Vedic injunctions, he used to visit the houses of Muslim kings, and thus he considered himself to have been converted into a Muslim. He was therefore always very humble and meek. When Sanātana Gosvāmī presented himself before Lord Caitanya Mahāprabhu, he said, "I am always in association with lower-class people, and my behavior is therefore very abominable." He actually belonged to a respectable brāhmaṇa family, but because he considered his behavior to be abominable, he did not try to place himself among the brāhmaṇas but always remained among people of the lower castes. He wrote the Hari-bhakti-vilāsa and Vaiṣṇava-toṣaṇī, which is a commentary on the Tenth Canto of Śrīmad-Bhāgavatam. In the year 1476 Śakābda (A.D. 1554) he completed the Bṛhad-vaiṣṇava-toṣaṇī commentary on Śrīmad-Bhāgavatam. In the year 1504 Śakābda (A.D. 1582) Śrīla Jīva Gosvāmī published an edited version of the Bṛhad-vaiṣṇava-toṣaṇī named Laghu-toṣaṇī.
(Sri Caitanya Caritamrta-----1:10:84-----purport).

Some of the books compiled by Śrīla Sanātana Gosvāmī were the Hari-bhakti-vilāsa, Bṛhad-bhāgavatāmṛta, Daśama-ṭippanī and Daśama-carita.
In the First Wave of the book known as the Bhakti-ratnākara, it is said that Sanātana Gosvāmī understood Śrīmad-Bhāgavatam by thorough study and explained it in his commentary known as Vaiṣṇava-toṣaṇī. All the knowledge that Śrī Sanātana Gosvāmī and Rūpa Gosvāmī directly acquired from Śrī Caitanya Mahāprabhu was broadcast all over the world by their expert service. Sanātana Gosvāmī gave his Vaiṣṇava-toṣaṇī commentary to Śrīla Jīva Gosvāmī for editing, and Śrīla Jīva Gosvāmī edited this under the name of Laghu-toṣaṇī. Whatever he immediately put down in writing was finished in the year 1476 Śaka (A.D. 1554). Śrīla Jīva Gosvāmī completed the Laghu-toṣaṇī in the year Śakābda 1504 (A.D. 1582).
(Sri Caitanya Caritamrta-----2:1:35-----translation and purport).