Why do not you use the Splunk IT Service Intelligence for this?
Splunk IT Service Intelligence: https://splunkbase.splunk.com/app/1841/
Or you could build the Advanced Dashboard using XML: http://docs.splunk.com/Documentation/Splunk/6.2.2/AdvancedDev/AdvancedDashboard
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?
Otherwise, jkat54's comment may apply.
This would require custom css and may be a bit too much to ask for on answers.splunk.com and more of a feature request / professional services request.
But check this to see if the SANKEY diagram would work: