node { shape: point; }

[ A ]
 -> [ B ] { point-style: square; }
 -> [ C ] { point-style: dot; }
 -> [ D ] { point-style: circle; }
 -> [ E ] { point-style: diamond; }
 -> [ F ] { point-style: cross; }
 -> [ G ] { shape: invisible; }
 -> [ H ] { point-style: star; }