Few tips from me.
Work on displacement first. Create plane, add turbosmooth modifier with as many iteration as your PC can handle without lagging, add displace modifier on top, set its strength to some arbitrary value (you will adjust that later) and plug displacement texmpap in its map slot. Procedural cellular would be the first candidat. Now play with settings, untill you feel happy about look.
Once you found good displacement map, move to colour. Plug AO to Corona material's diffuse slot, choose calculate from inside mode, set occluded and unoccluded colours to what you need (you can set them to some contrastish colours at first to better see what's going on), set colour spread to 1 and adjust max distance untill you feel happy with width of secondary colour. Now, set colour spread back to 0 and you should have pretty decent result. Interactive rendering is highly recommended while playing with material settings.
Here's my very quick attempt with described technique. With some more time and effort, you can achieve even better result.