digraph {
    size="5,4"
    1 [label="  start state  ", shape=circle, style=filled, color=blue]
    2 [label="start/end state", shape=doublecircle, style=filled, color=blue]
    3 [label=" internal state", shape=circle, style=filled, color=red]
    4 [label="  end state    ", shape=doublecircle, style=filled, color=green]
}