Are you looking to create something like this?
When creating the edge, press and hold SHIFT before you press the mouse on the start node and also press and hold SHIFT when you release the mouse on the target node. This will result in the edge starting/ending at the current mouse position instead of the center of the node. Additionally, create at least two bends for the edge.
As an alternative to holding down SHIFT, you can also create an edge as usual, (i.e. one that starts and ends in the center of its source and target nodes), add a couple of bends and adjust the edge's Source Port X, Source Port Y, Target Port X, and Target Port Y properties.