OmniGraffle can import documents using a subset of the GraphViz DOT file format.

Command	Entity Types
URL (not on graphs)	edge/line, node/shape
arrowhead	edge/line
arrowtail	edge/line
color	edge/line, node/shape
dir	edge/line
fillcolor	node/shape
fixedsize	node/shape
fontcolor	edge/line, node/shape
fontname	edge/line, node/shape
fontsize	edge/line, node/shape
headlabel	edge/line
label	edge/line, node/shape
labelfontcolor	edge/line
labelfontname	edge/line
labelfontsize	edge/line
orientation	node/shape
rank	node/shape
rankdir	graph/page
shape	node/shape
style	edge/line, node/shape
taillabel	edge/line
width	node/shape

All arrow head types are supported, but a few do not correspond exactly to OmniGraffle arrow types. The inv, invdot, invodot, and invempty arrow types are replaced with the closest available OmniGraffle line ending.