This is because all your relationships have the same type. You could add a property to the relationship type that is your middle column and then use that as the caption for the relationship. Or if it is important to have different relationship types for each relationship, you could use the file filter to filter the file and create the four different relationship types (see attached anigif).

Maybe your nodes also should have different labels other than all being called "Node". But your simple data doesn't seem to have obvious candidates.

Hey, what you're seeing here are labels you've assigned to the nodes. You can configure the Explore application to use different Text properties for your captions in the graph.

That said, it probably doesn't make too much sense to have them labeled as Source and Target labels. You could just try giving both source and target labels and then use then call the identifying label in each end of the relationship the property . See the attached anigif, hope that helps.