You've done well with what you've got, looks like a bunch of your cables have to be plugged in further towards the middle of the MB than usual so those are always gonna look messy, if you got some matching colored cables though it'd blend in better.
Also might be an idea to fashion some rubber grommets to hide the cables you can see through the cable management holes. Can't think off the top of my head what you could cut to make them without buying the material though.