dot_state_machine.gv

digraph finite_state_machine {
    rankdir=LR;
    size="8,5"

    node [shape = circle];

    node [shape = doublecircle]; s1;

    node [shape = doublecircle]; s5;
    
    s1  -> s2 [ label = "t1" ];
    s2  -> s3 [ label = "t2" ];
    s3  -> s1 [ label = "t3" ];
    s3  -> s4 [ label = "t4" ];

    s5  -> s6 [ label = "t5" ];
    s6  -> s7 [ label = "t6" ];

    s7  -> s8 [ label = "t7" ];
    s4  -> s8 [ label = "t8" ];
    
}