edge { arrowstyle: filled; }
graph {
colorscheme: x11;
flow: south;
title: G;
}
group {
align: center;
fill: inherit;
}
( cluster_first
[ a ]
[ b ]
) { label: first; }
( cluster_second
[ p ]
[ q ]
[ r ]
[ s ]
) { label: second; }
[ a ] --> [ b ]
[ b ] --> [ q ]
[ q ] --> [ r ]
[ r ] --> { style: bold; } [ a ]
[ r ] --> [ s ]
[ s ] --> [ p ]
[ p ] --> [ q ]