Have a look at this test project - maybe there are some things in there that would be useful for you. The Bump Map filter gives a nice displacement effect (driven by a modified Clouds generator) and the Indent filter on top of that adds an element of depth.
The Bump Map filter isn't doing anything with the colours, it's just "stirring up" the layer it's applied to. The colours come from the two gradients and I'm masking between them so we get a nice variation. So dive into the gradients if you want to change up the colours.