4e originally had the Dragonborn not resembling the dragons in terms of colors, and there was no sure way to know what kind of breath weapon they had (until they used it). The association between color and breath weapon for Dragonborn is a 5e thing.Now another question is why it is like that, and indeed why it is like this for dragonborn. After all, both are species only very distantly related to true dragons, so it would be a bit weird if they just happened to have the same colour categories with associated breath weapons (should they have any.)
Pathfinder has the Kobolds being color-coded.I've come across that in several adventures, going back as far as third edition. No special abilities, but colour and markings indicate tribe or draconic affiliation.
Racism.
Next question.
Yeah, comes from 3rd edition.