Are Magic: The Gathering booster packs "color random"?
If you're talking about regular (also called 'Draft') boosters: their color distribution is completely random, except that some sets may have a somewhat skewed color distribution themselves, e.g. there might be more black cards than white cards in the set; then, booster packs will contain (on average) more black than white cards. An example of this Torment; from the checklist, it's also clearly visible that it's a set which contains a high number of black cards.

The only thing that is not random is the rarity distribution; each pack contains


  one marketing card, one basic land, ten commons (one possible premium card in any rarity), three uncommons, and one rare (occasionally, about one in eight packs, replaced by a mythic rare).


(source: Gamepedia)




  Can you get booster packs by color?


Actually, it turns out you can. As @murgatroid notes in the comments, beginning with Dominaria in 2018 Wizards started selling 'Theme boosters' (scroll down to the end of the article) with a fixed color distribution (depending on the set, a single color or a combination of two colors).