The only site that I found said full sun......
It's native to Yemen, so bear that in mind next summer.
Oh, it also said that the flowers are foul smelling!!

Full sun turns it green to brown. Sun to shade turns it green to green (which looks healthier) although many light shaded plants take on a darker green to induce Chlorophyll take up of available light with some plants going to full burn out on full light exposure , seems to me this plant needs a dapple sun shaded exposure
This plant has been left out side all year trying to get it to flower when and if it does, I will bring it inside and the odour may drive out the other flower who is blooming awful on occasions.

Check the photo out on this page........

http://www.cactus-mall.com/stapeliad/picture2.html

That one has more of a brown colour to it. Is that how yours went?

Here in the desert, we grow it on the east side, under laths, or under 50% shade screen. It seems to flower during the hottest part of the year, too. Maybe putting it on the south side of a wall--for heat buildup--but to the east of a bush--for afternoon shade--would be one plan.