I suggest the folowing color combos for coho.
Brown/orange
olive/orange
pink/blue
blue/silver, such as pearl uv polar chenille , or krystal flash
black red
and my favorite all around jig purple/cerise.
I always tie in some kind of sparkle shiny material into my personal coho jigs although it is certainly not essential.
Another thing to try is twitching jigs, I will be posting up a video on this technique as soon as some numbers of coho arrive worth fishing for.
Twitching jigs I use can be viewed on my website
www.bentrods.ca.
I also will often just use a 1/4 ounce jig with 3" curly tail grub on it just as you would for Pink Salmon, excepting I use a bunch of different colors of grubs, such as purple, white, black, red, orange and if the water has color chartreuse.
Best of luck with the Coho this year, hopefully the run is a good one.