digraph space {
    node [shape = circle, height = 0.6, fontname = "monospace", fixedsize = true, fontsize = 12];
    edge [fontname = "monospace", fontsize = 12];

    node [shape = circle];
    START;

    node [style = filled];
    SPACE;

    START -> SPACE [label = "[<space>\\t\\r\\f\\v]"];
    SPACE -> SPACE [label = "[<space>\\t\\r\\f\\v]"];
    
}