I painted the exact same vest: some lighter paint completely disappear on this material.
before applying lighter paint I suggest you spray the zones with a very covering and thick white primer, and then apply the color.
I did that to get some desert and reddish brown on a dark OD one
paint reacts weirdly on this material, and will melt from bug spray if you use it.you will most probably get a quite messy result in the end, not flashy like factory colors.
it's good if you go for that kind of look
and now I just want to do it again, I'd do it if this vest wasn't so goddam uncomfortable i.m.o