All auratus are born yellow. As they age the males start to change color. He's just in the middle of that color change. Eventually he will look like this:
The shaking is a display. Flashing on rocks is sometimes a display but can also be a sign of disease. The shaking is either to impress a mate or to let other fish know he is more dominant. Depends on who he is displaying to.
For the flashing I would check your water parameters to make sure nothing is out off.