The logic of how vertices(nodes) and edges(links) are drawn in Graph Visual is rather simple. The Graph works on a typical graph data database Graph Database principle. 

The Data needs to have a Source(From) Node IDs, Target(To) Node Ids and Value, that defines the node size and value for the vertices(nodes).

There are few additional properties, that you can define through the fields pane, which means you can controll this on data level not just through formatting options. The additional fields are divided into 4 groups:

• Source Node properties
• Target Node properties
• Link properties
• Node and Link Tooltips

More information about all the fields can be found under "Setting up fields " section of the Graph visual documentation

Graph Visual also support multiple layout forms:

The Drill Down Graph visual is also the first graph structure visual, that supports bi-directional links. Here is an example of how the data should look like and a visual example:

Additional tools inside chart (lower left corner):

• " Zoom slider" allows to manually zoom in or out
• " Fit-to-screen" mode automatically zooms to the most suitable
• " Reset" button resets all the locations for the nodes. If Focus mode is used then it will also collapse everything to the initial state.
• "Expand All" button on toolbar. Clicking on the button expands all nodes to their maximum expansion level. Note: Works only for focus nodes.
• "Collapse All"  Clicking on the button collapses all nodes to their maximum collapse level until the initial focus node level is reached. Note: Works only for focus nodes.
• "Expand Direction" Clicking on the button adjust the expansion direction, whether it is from ‘Source to Target’, from ‘Target to Source’ or bidirectional (target to source, as well as source to target).
• "Save State" button on toolbar. It freezes the node arrangement as it was in the moment the button was clicked.
• "Display Mode" button on toolbar. Clicking on it switches between showing all nodes and focus nodes only.
• "Explore" button on toolbar. If Explore mode is on, clicking on the node will drill through further layers of data. If Explore mode is off, clicking on the node highlights it only.
• "Unhide Nodes" button on toolbar. Clicking on the button unhides all the hidden nodes. Note: button is visible only if the node has been hidden already through the tooltip functions.
• "Search" adds a search box in the lower right part of the visual.