Power cables should not be coiled unless you want induction loops, lower efficiency, and waste heat.
Ideally, the cables would be the minimum length needed as I understand it. For excess cables though, is there a better solution to organize it to avoid coiling?
For an install like this I would make everything to size. Quite a lot of this could be cleaned up by using only 1 or 2 multi tap power supplies that had a terminal strip for the output. The original cables could be used with the barrel plugs/USB/ whatever on the device end, and the other end cut to length.
For cables it's much better to use something like this photo, if you have many cables that need to be routed the same way there are cable ties with a ring tab that accepts a screw or nail.