Ok, let's look at the fluff behind the Wraithguard. They are artificial wraithbone constructs which are brought to 'life' by the addition of the soul of a deceased Eldar warrior. As a result of this, they were often mighty warriors and Exarchs, and are held in very high regard and with reverence by the living Eldar.
So, I was thinking, perhaps rather than painting (or whatever Eldar do to make things colourful!) them in a 'standard' scheme, perhaps they would paint them with symbols of the deceased warrior, such as heraldry and Aspect shrine symbols and colours, as a sign of their respect? Rather than standardising them as if they were mere robots, surely the Eldar would want to preserve the individuality and pride of the warrior whose soul is guiding the construct, and what better way to do this than with impressive and unique paint jobs?
Overall I'm thinking of a look almost like that of a unit of Bretonnian Knights, or perhaps similar to Harlequins. I haven't really got the painting skills to carry it off to much of a high standard, so I'm afraid there will be no pictures from me...
Any thoughts or comments