Hi Chris
Well you could do it pretty much any colour, if you go by reference pictures you can find of a house, as materials differ in colour depending on what the local area supplies are.
Here is the actual model you have
Looks pretty good. Do you get everything in the picture, shutters etc.?
The roof looks to be representing a house with clay roof tiles so they would be a terracotta type colour with variations in tone. Walls look to be a cement type rendering over brick or block work. This could be painted although judging by the representation of a fairly poor and run down property I'd say go for a stone colour , buff maybe with variations of staining from age and weathering.
Hope that helps
Try Googling under "images" in a search, putting in various combinations. Should be loads out there.
Alan