It has been said before, but I'll say it again: the idea of the "gray man" is a myth, a joke. In the event of a true SHTF situation, anybody and everybody with stuff will be a target, regardless of how they appear. There is no "blending in" with a society that is collapsing in on itself. If you look like you have lots of stuff, you'll be an early target. If you look like you have some stuff, you'll be a target of opportunity. Best case scenario is to, using the military term, appear as a hard target, the guy would be scavengers, thieves, etc, wouldn't want to screw with. Even then, you're still a target, just not one they'll want to openly confront early on. If you really have to bug out, you need to avoid unnecessary contact with people in general. Don't be seen. Camouflage helps in some areas with this, but isn't necessarily crucial. Staying off main roads, avoiding gathering points, traveling at night, and generally getting out population centers is a good idea.
In a less serious situation, this might not always be the case, but the principle is still the same.
Personally, my BOB is solid color, Coyote Brown. I would prefer it to be MultiCam (like the rest of my kit), but I can live with CB.