Just write one yourself. It's really trivial to do.

    Foreach node
      Foreach node.transition
        Matrix(node, transition.event) = transition.destination

And the other way:

    Foreach node
      Foreach event
        Destination = matrix(node, event)
        Graph(node).add(event, destination)

I wrote a tool at work for this. Using python to read in an Excel workbook with states and events in rows and columns that outputs a PlantUML state machine description. Worked really nicely, but not available for open sourcing at the moment.

Using python it's quite straightforward to convert between numpy arrays and sparse arrays, which are basically the graph represtation of the same data.