Ping!
I humbly suggest that los periódicos del barrio, as well as the Mexican radio stations announce el color del día. It could save lives. Also, the Sheriff ought to publish color-guide maps, so that one can wear the right color in the right 'hoods. Many gang members carry small knapsacks ... apparently for costume changes, although spare ammo could also be helpful on pharmaceutical delivery and assassination runs.
Remaining problem: tattoos. So stay covered up. Another way to limit gang activity is to end the sale of large-bore exhausts for small Hondas. I have also seen gang-bangers driving even cheaper Korean and Malayan automobiles. A shocking lack of standards!