microplane rotary grater
I don't know what the shredding drum is like on those but otherwise it's just the old standard cheese grater shape. I suppose it would work for coconut if you cut the meat into small pieces and removed the skin, but at that point I think you might as well just use a food processor on it which would certainly be less work. Grating a whole coconut with on of those hand thingies will take a long time.
What are you trying to grate the c/nut for? To make coocnut milke, or for shreds, or ? That would have a bearing on the best tool for the job.