digraph tree
{
size="8,11!";
splines=true;
fontsize=30;
ranksep = 0.1;
subgraph clustertasks
{
label = "Pipeline:";
edge[minlen=2];
node[fontsize=20];
t0[style=filled, color=olivedrab, label="task1", shape=octagon, fillcolor=olivedrab, fontcolor=black];
t1[style=filled, color=olivedrab, label="task2", shape=octagon, fillcolor=olivedrab, fontcolor=black];
t0 -> t1[color=gray, arrowtype=normal];
t2[style=filled, color=olivedrab, label="task3", shape=octagon, fillcolor=olivedrab, fontcolor=black];
t1 -> t2[color=gray, arrowtype=normal];
t3[color=gray, fontcolor=gray, shape=tripleoctagon, label="task4"];
t2 -> t3[color=gray, arrowtype=normal];
}
}