digraph Perl
{
graph [ rankdir="TB" ]
node [ shape="oval" ]
edge [ color="grey" ]
"8" [ color="invis" label="" shape="point" width="0" ]
"15" [ color="invis" label="" shape="point" width="0" ]
"8" -> "15" [ color="cornflowerblue" label="This edge's color is blueish" ]
}