I understand what you need, but I was asking you to verify that you are calling this:
and not this:
The first method does not lay out the graph's vertices before drawing the graph, so I would not expect any vertices to move after calling the first method.
If you are indeed calling the first method, is there anything else you are doing to the graph before redrawing it that might affect the vertex locations? Or are you simply setting some Visibility key values and then calling the method?