That's probably the most interesting looking Hunstman I've ever seen. Not 'cause it's actually that interesting (it's a little interesting) but because every hunstman I've ever seen has been a common boring brown.
For the one in the pic, base white, drybrush ... Dryad Bark maybe in select spots covering ~60% of the mini, Agrax Wash everything, and you'd be 90% of the way there. Maybe a very light drybrush with your favourite off white to bring out the highlight on the bits you wanted to remain white.