http://www.graphviz.org/doc/info/colors.html

线颜色

subgraph cluster_api {		#rank=same;		node [style=filled];		label = "api";		#color=blue		api [label = "api.netkiller.cn"];		api->redis [color="red"];		api->mongodb [color="green"];		api->oracle [color="blue"];			}

http://www.graphviz.org/doc/info/shapes.html

digraph G {  	A -> B [arrowhead="vee"]	AA -> BB [dir="back" arrowtail="vee"]	AAA -> BBB [dir="both" arrowhead="vee" arrowtail="odiamond"]}