Like any other fish/predator caught on art lure they most defnitely have a colour preferance which differs from day to day. But i do agree that if they are there in numbers they will take any colour jig, some colours might just outfish others. In my years experience certain colours/profiles require different jigging effects. Moslty a regular rithmic motion works best. Also they love vibrations if rithmic as well. Example would be, when fishing handline, hands over the rail, palms flat fingers facing down, use your middle fingers point to lift the line up against the rail towards your palm. Get the speed right as to not get slacks inbetween the motion. Keep steady tension on the line as you move it up and down with your finger. Also a very good technique is to, with your hand off the railing, pull the line up and down about 5 inches as fast as you can without getting slack line inbetween, ie keeping steady tension. The absolutely loooove that. Never leave your jigs dead in the water! The key to pulling them in is to never strike!!! Just pull steady with no slack line inbetween pulls once hooked. Also dont try to force it too fast as the break off quite easily leaving you with a tenticle, this seems to happen more often when the water is warm. Above 20degrees about. We work with 2 jigs on a sinlge line. A coloured lead jig on the bottom, and inline about 2 fathoms up a float/fish jig. This helps cover more depth as well. As for the depth, thats very hard, usually the calmer the conditions the shallower they move.
Hope this helps. Chokka is on the scarce side this year. But best of luck!