Switch back to Style Editing Mode by clicking the Style Editing button in the vertical toolbar.

To add a legend, choose Edit>Options and check Legend, then click OK. The Legend option adds a legend to your diagram.

The legend is an explanatory table listing graphic symbols and explaining their meanings.

To display the legend as an independent window, uncheck the Inlaid option in the Position tab of the Styling Customizer.

By default, the legend shows two columns, one for nodes and one for links, with an entry for each user-defined type.

With Legend selected under Options so that the Styling Customizer for the legend is displayed, you can customize the general appearance (font, spacing, colors) of the legend in the Display tab and the position in which the legend appears in the Position tab.

You can also change the contents of the legend in the Columns tab of the Styling Customizer