digraph G {
    margin=0;
    a [style=bold, label="and"];
    s [label="twist-01"];
    d [label="shout-01"];
    p [label=<<FONT COLOR="red">S</FONT>>,fontname=helvetica];   

    a->s [label="op1"];
    a->d [label="op2"];
    s->p [label="ARG1"];
    d->p [label="ARG0"];
}
