It could be tricky to implement a zoom feature (to zoom-out the skill tree) due the nature of the UI of the game being very tiny with 8x8 assets. I'll try to find out a solution
It might help to just grey out maxed skills? That way, only skills that have yet to be fully purchased would stay in colour, making it more visually obvious where to go next.
Related; the skills tree isn't centred on screen when you enter it. I needed to scroll a bit to the right every time to get to the column with the hazard stuff, but there was extra space available on the left every time.