Perhaps the ITSI app (one of the few paid-for apps) may help?
The second screenshot in the Splunkbase entry for the ITSI app is something I saw a demo of being created (or something very much like it). It was completely ad-hoc, built based on a Visio diagram used as a template. The point being that it can fairly arbitrarily do this sort of "arranging" of things.
That being said, have you tried rearranging the order they are in on the dashboard?