Firstly, through the use of icons from the excellent collection at http://game-icons.net/, added to those that I've already made myself.
Secondly, by making a link between the colours associated with each player faction and an extra faction mana bonus for occupying areas of their faction colour. This idea came out of trying to simplify the range of colours and their meaning, plus my wanting to address the slight confusion on whether the colour of an area was important beyond card use.
EDIT 21/Nov/2013 - After thought / discussion, the mana bonus would be too imbalanced, with the red player doing badly and the ice player doing too well (all those sea areas). Currently, thinking about making it a plain +1 in combat advantage.
So, a series of new game charts, plus the list of the new encounter cards that will replace the defender tokens...