I understand these questions as conversation openers rather than actual questions.
Having one “favorite” anything let alone something as vague as a color, is impossible. And the person asking doesn’t really want a specific answer, they just don’t know what to say so they also follow a scripted questions they’ve heard before.
So I will respond with something like “I listen mostly to Genre A and Genre B. I’ve been to the concert of Band Z recently. What’s the latest concert you’ve been to?”
Or “I try to wear bright colors in the winter, to try and compensate for the gray days and cold nights”
Something related to the opening question but doesn’t have to be a singular answer. More like your general opinion on colors followed by a question so the other person has something to latch onto for their turn in conversation.