Go to a thrift store or rummage sale and pick up the totally unwanted 10 foot or longer old style parallel printer cables. You can usually get them for 50 cents or less.
Cut the ends off and slide the wire bundle out. Most have all 25 wires in place (look for thicker bundles--about 1/2" diameter instead of 1/4"). Each wire typically is a totally different color or color/dash combination.
Be aware these are ONLY good for signal cables... e.g. buttons and joysticks, as they typically are very thin wires like 22 gauge or smaller. Do NOT use them for carrying any amperage like to light bulbs as they will get hot and be a fire hazzard.