For dependency diagrams, the convention is to use the output of dependency:tree
i.e.
[user:maven-test]$ mvn dependency:tree
[INFO] Scanning for projects...
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building maven-test 1.0
[INFO] ------------------------------------------------------------------------
[INFO]
[INFO] --- maven-dependency-plugin:2.1:tree (default-cli) @ maven-test ---
[INFO] maven-test:maven-test:jar:1.0
[INFO] +- junit:junit:jar:3.8.1:test
[INFO] +- com.sun.jersey:jersey-json:jar:1.9.1:compile
[INFO] | +- org.codehaus.jettison:jettison:jar:1.1:compile
[INFO] | | \- stax:stax-api:jar:1.0.1:compile
[INFO] | +- com.sun.xml.bind:jaxb-impl:jar:2.2.3-1:compile
[INFO] | | \- javax.xml.bind:jaxb-api:jar:2.2.2:compile
[INFO] | | +- javax.xml.stream:stax-api:jar:1.0-2:compile
[INFO] | | \- javax.activation:activation:jar:1.1:compile
[INFO] | +- org.codehaus.jackson:jackson-core-asl:jar:1.8.3:compile
[INFO] | +- org.codehaus.jackson:jackson-mapper-asl:jar:1.8.3:compile
[INFO] | +- org.codehaus.jackson:jackson-jaxrs:jar:1.8.3:compile
[INFO] | +- org.codehaus.jackson:jackson-xc:jar:1.8.3:compile
[INFO] | \- com.sun.jersey:jersey-core:jar:1.9.1:compile
[INFO] +- com.sun.jersey:jersey-server:jar:1.14:compile
[INFO] | \- asm:asm:jar:3.1:compile
[INFO] \- com.sun.jersey:jersey-client:jar:1.14:compile
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
It turns out that this plugin can output to a visual graph.
See: Maven Dependency Plugin - Output type.
If you are using IntelliJ IDEA, it has a built in Maven dependency graph as well.