The latest version of Sims 4 Studio for Mac - Candy Apple - has just been released. It supports High Sierra and now includes the ability to recolour objects! You can get it here -
http://sims4studio.com/thread/6065
It's beta so may be a little buggy but wow, I love the support for the Mac community
Comments
Probably best to ask over on the S4S forums but have you looked in the Preferences in S4S? Blender should be in your Applications folder.