You can create node groups to make complex graphs easier to read and to scroll. The first step is to select the nodes you want to group together.
Open the context menu and choose "Select Range To...". Then choose the last node of the chain you want to select. Once you have done that, use the "Group" command in the context menu to create a group. You can collapse and expand this group by clicking on the arrow icon on the left. You can also resolve the group by clicking on the "Ungroup" command in the context menu.
Limitations
The nodes have to be in a suitable range, otherwise the selection is not possible. All transitions have to start and end within the range. No transition can leave the selection, because the logic has to be part of the selection. Consider using empty action nodes to help closing off a group of nodes.