RMB Click, hold and drag: Move the graph
Mouse Wheel: Zoom in / out
LMB Click on node: Select node
LMB Click, hold and drag in empty space: Marquee selection
LMB Click on selected node(s), hold and drag: Move Selected item(s)
RMB click in empty space: Open the -Graph Action Menu
LMB Click on node pin, hold and drag out to empty space: Open the Graph Action Menu
LMB click on node pin, hold and drag out to other pin: Make new connections Ctrl + LMB click on node pin with existing connection, hold and drag top new node pin: Move an existing connection.
Alt + LMB click on node pin to break connections.
Double-click on a wire to insert a reroute node (for keeping things tidy).
You can ...