graph G {
  graph [overlap=false,splines=true];
  node [shape=circle,fontname="Helvetica",style=filled,fillcolor="white"];
  edge [fontname="Helvetica",penwidth=1.0];
  a1 [label="C"];
  a2 [label="C"];
  r1 [shape=point,width=0.08,label=""];
  a1 -- r1 [label="·",color="red"];
  r2 [shape=point,width=0.08,label=""];
  a2 -- r2 [label="·",color="red"];
}