Have you a UV lamp? That will kill the mould without harming the camera - but short of that stick in the sun.
I have a huge Century process camera which arrived thick with dust and mould. I scrubbed it all down with a sponge and some hot water and washing up liquid, then left it outside in the sun to dry. It did the trick.
The dye in the leather covering and bellows may well be water soluble and even more likely will be alcohol soluble, so too much rubbing with either may take the colour out... but that isn't a completely bad thing. Being gentle with a damp sponge and bringing the dye back up to the surface can actually revitalise the colour and the finish. After that you seal it again (when completely dry) with a covering of clear wax (shoe wax).