Some radial graph

Fooling with Graphviz:

Radial graph

digraph G {

graph [root="a",
ratio="auto",
outputorder="edgesfirst",
bgcolor="#eeeeee",
overlap="false"];

node [shape="rect",
style="filled",
fillcolor="white"];

"a" -> "b";
"a" -> "c";
"a" -> "d";
"a" -> "e";
"a" -> "f";
"a" -> "g";
"a" -> "h";
"a" -> "2";
"a" -> "3";
"a" -> "4";
"a" -> "5";
"a" -> "6";
"a" -> "7";
"a" -> "8";
"a" -> "9";
"a" -> "10";
"a" -> "11";
"a" -> "12";
"a" -> "13";
"a" -> "14";
"a" -> "15";
"a" -> "16";
"a" -> "17";
"a" -> "18";
"a" -> "19";
"a" -> "20";
"a" -> "21";
"a" -> "22";
"a" -> "23";
"a" -> "24";
"a" -> "25";
"a" -> "26";
"a" -> "27";
}

Rendered with: $ twopi -Tpng sample116.dot -o sample116.png

This works quite well with just a handful of nodes, but with node numbers in the dozens and hundreds, edge length for the outer nodes increases dramatically. There doesn’t seem to be a way to pack this sort of graph tightly for lots of nodes.