Drawing a graph on Canvas using points from a list

I have points from a list and I have managed to draw them on a Canvas
but the problem is, I can not make the graph plot in the middle of the Canvas and more clear. The images below show the blocks and result. I don’t know where I can change to make the graph more clear and in the middle of the Canvas?



3-Output graph ploted from the blocks

4-The output graph should look more clear like this (Reference)