They should be color-coded; there are 4 buttons that interface with that trackball.
There are redundant wires though. I'm not sure why they make them that way, unless you want to go crazy with buttons on your control panel (maybe 4 on left side and 4 on right for left and right handed players? Not sure).
Also, the terminal ends are different sizes.
I just keep my extra wires tied up and tucked out of the way.