digraph g {

  rankdir = "UD"

  {rank=same; 22}
  {rank=same; 18; 19; 20; 21}
  {rank=same; 14; 15; 16; 17}
  {rank=same; 9; 10; 11; 12; 13}
  {rank=same; 3; 4; 5; 6; 7; 8}
  {rank=same; 1; 2}

  1 -> 2;
  2 -> 6;

  3 -> 4;
  4 -> 5; 4 -> 10;
  5 -> 1; 5 -> 4; 5 -> 11;
  6 -> 7; 6 -> 12;
  7 -> 11;
  8 -> 7;

  9 -> 10; 9 -> 15;
  10 -> 3; 10 -> 5; 10 -> 15;
  11 -> 10; 11 -> 12;
  12 -> 11; 12 -> 8; 12 -> 13; 12 -> 16; 12 -> 6;
  13 -> 16;

  14 -> 15; 14 -> 19;
  15 -> 9; 15 -> 10; 15 -> 16; 15 -> 19;
  16 -> 15; 16 -> 17; 16 -> 11;
  17 -> 20;

  18 -> 19;
  19 -> 14; 19 -> 16; 19 -> 22; 19 -> 20;
  20 -> 19; 20 -> 21;
  21 -> 22;

  22 -> 18; 22 -> 19;

}