There are 2 types of CAT5 cable... stranded and solid core.
The stranded core cable is designed for general usage. (under 20 feet) Used for making patch cables etc, it's individual wires have several thin strands of copper wire inside. this allows it to be flexible.
The solid core is designed for long distance horizontal and backbone cable runs inside walls and ceilings where it will be installed and NEVER EVER moved. It has low attenuation (lower than stranded cable) making it more suitable in these long runs.
Stranded cables are expensive to manufacture and as such are more expensive than solid conductor cables for the equivalent length. The result of this, is often when you purchase bulk cable, it is often the sold variety to cut down on overhead and increase profit... except solid cable is no good for wiring panels like this.
If you feel you MUST go the CAT5 cable route, use stranded wire cables... but really, regular old wire like what is found in every other arcade game in existence is just fine. You aren't going to be leaving the panel open like some kind of car meetup anyways.