Have you looked at the graphviz plugin?
You can type this
[graphviz engine=circo]
graph {
a [label="Discourse Plugins"]
a -- "discourse-adplugin"
a -- "discourse-affiliate"
a -- "discourse-cakeday"
a -- "discourse-canned-replies"
a -- "discourse-calendar"
}
[/graphviz]
To make a graph like this: