If your link is Orthogonal, you can set AvoidsNodes to true.
If your link Style is Bezier, you can change the Curviness (either positive or negative) to try to avoid the node in the middle. However, you need to do this for each link separately, since unlike AvoidsNodes when the link is Orthogonal, GoDiagram will not automatically calculate a value of Curviness for you, since there might not be any reasonable value that will work.