A bit more information about your warband would be helpful.
If you want your Ogre
to look more like a hired sword, ie not of yur warband, then you can paint him as you like. Here is a standard Ogre
Now if you want to align your Ogre
with your warband, then you still have many options. For human warbands you could paint his clothes as if they are patched together from flags of the region, or you could give him signature weapons for your warband. In the case of other warbands such as Chaos etc, it becomes more of a modeling issue than painting.