I dont know if they hold any significance as of yet, but comparing them to WC3 models. The red one could be Varimathras or Tichondrius, the blue is Mephistroth, purple is Balnazzar, and yellow is Anetheron.
... Or once again I am over thinking things.
Either way, with the Legion poking its malignant buns out the door again, all alive and kicking, it may be something worth looking in to.