I don't think jig color rerally matters, or even if the head is painted. Coho's just don't care. Twitching does work better in slow seams of the river but just casting as you go down the river will likely find you other types of water and places that the fish are holding in. We have located fish along the edges of the river in places that you would never expect them to be, on the next trip we caught them there again sometimes in only 2 feet of water. Fish bright colors first then go to dark ones when fishing the same hole after the fish turned off the bite.