Problem
It is difficult for me to find the current note in the graph.
Proposed solution
I would therefore suggest a marker for the current note - a purple ring.
If there should subsequently be a button to center the view around the current note, you could animate the ring briefly immediately after centering to draw attention to it. The animation could be a brief increase and then decrease of the ring. The power-ups from Super Metroid (SNES) come to mind. 