digraph {

  node [shape=circle,fontsize=8,fixedsize=true,width=0.9];
  edge [fontsize=8];
  rankdir=LR;

  "do" [shape="circle", style="filled", color="green"];
  "approved" [shape="circle", style="filled", color="red"];

  "do" -> "approval";
  "approval" -> "approved";
  "approval" -> "do";

}