Usually the graph is started in Orbit view mode going around the graph. To take control of the view angle, hold down the right mouse button and drag the mouse. You can use the mouse wheel to zoom in and out. The three different camera modes of Orbit, Fixed and Free can be cycled through by pressing F on the keyboard. An icon will appear in the top right to indicated which mode that you have currently set. Use the keys W (forward), S(back), A(left), D(right), Q(Up) and Z(Down) to move the camera.