Kiryu2012 said:
She doesn't turn 'invisible', she just changes her colors to match her surroundings. And there's no way in hell Kong would give her an opportunity to run away and hide to blend in with the environment. And that's out of character for Indominus anyway, since she's never tried such a tactic when fighting anything around her size. She instead just charges in head-on, which would go badly for her against the likes of Kong.
That would still make her nearly invisible to Kong and there is no reason to assume it would be out of character for her to use such ability again other large animals, she didn't use her with Rexy because she either has the time and because it wasn't necessary.
She may not start the fight in that way, but it wouldn't take long for the hybrid to understand that Kong is not standard beast and she will understand that she would need to use all her tricks and any opportunity for win the fight.
And yeah Kong will try to stop her from camouflage herself, but that would probably happen only after I-Rex would have used such tactic the first time.