Using Visant to graph Ant target dependencies

vizfile.xml

<project name="vizfile" default="main">
    <taskdef name="vizant"
             classname="net.sourceforge.vizant.Vizant"
             classpath="${user.home}/.m2/repository/net/sourceforge/vizant/vizant/0.1.2/vizant-0.1.2.jar"/>
    <target name="main">
        <vizant antfile="./build.xml" outfile="build.dot">
            <attrstmt type="graph">
                <attr name="ranksep" value="1.2"/>
                <attr name="nodesep" value="0.5"/>
            </attrstmt>
        </vizant>
        <exec executable="dot">
            <arg line="-Tjpg build.dot -o build.jpg"/>
        </exec>
    </target>
</project>

Run with ant -f vizfile.xml.

Visant isn't in Maven, so you'll need to download the jar and put it somewhere yourself. I installed it in my local Maven repo at the logical place.