If you done your research properly, the casing is polycarbonate to be precise. That means you probably wouldn't find any grippier phones out there.
The polycarbonate ain't glossy so it's quite hard to get dirt on, but the glass is just like any glass, it's touchscreen, so fingerprints is something you would expect.
But then, I'm using black one, so cyan could be a different story and unwanted pigments could be more conspicuous.
If stubborn paint does get onto your cyan casing, then the very last resort could be sanding it off haha. Mind you, the polycarbonate itself is cyan, so it would still have the same colour if parts of it is to be shaved off.