Yellow:
It is a prestigious amalgamation of folks, commonly in South Texas and mainly of Hispanic background, but by no means limited to Hispanics. There are a ton of white folks/Gringo's that are Cool Arrows, in fact in the RGV and in South Texas many of the Hispanics consider all Gringo's Cool Arrows.
It is kinda like a club, you just have to ask around. Like I said, when you get down to Laredo, and if you survive the heat, just ask folks if they are a Cool Arrow or not. It is all tied back into the Comanche Indians and such of the area.