The Fedwiki uses Graphviz 
to draw graphs of the sort that have nodes and edges. Graphs are described with the Dot notation plus Fedwiki extensions.
Create a Graphviz paragraph with the factory:
Pick Graphviz
This will give you an empty text box, which is disconcerting. Type the Keyboard Shortcut CMD-I to open the About Graphviz Plugin for documentation.
Edotor is a website that helps you interactively create graphs. It also has links to documentation.
See also Create a Graph Showing Incoming and Outgoing Links. That allows you to create diagrams like this:
DOT strict digraph rankdir=LR node [style=filled fillcolor=lightyellow penwidth=3 color=black fontname="Helvetica"] HERE NODE node [style=filled fillcolor=white penwidth=3 color=black] LINKS HERE -> NODE node [style="filled,rounded,dotted" fillcolor=white] edge [style=dotted] BACKLINKS NODE -> HERE STATIC strict digraph {rankdir=LR node [style=filled fillcolor=lightyellow penwidth=3 color=black fontname="Helvetica"] "Page Graph Links To HERE" node [style=filled fillcolor=white penwidth=3 color=black] "Page Graph Links To HERE" -> "Step-By-Step Page Graph" "Page Graph Links To HERE" -> "Step-By-Step Page Graph" node [style="filled,rounded,dotted" fillcolor=white] edge [style=dotted] "Step-By-Step Page Graph" -> "Page Graph Links To HERE" "Page Graph Deeper Levels" -> "Page Graph Links To HERE" }
... using Graphviz Algorithmic Markup.