Coat is distributed via Sourceforge in a ZIP file containing coat.jar and coat-src.jar. Download.
Just copy the jar file wherever you want. You need to reference it explicitely by the "-cp" or "-classpath" parameter of "java" or put it in the CLASSPATH environment variable to run.
Coat comes with two demonstrations, one in a pure Swing UI and the other one using JOGL (the Java OpenGL binding).
Both supply a toolbar (not shown in the screenshots of this site) which you can use to operate on the graphs.
To start the Swing demo, double-clicking the jar file or "java -jar coat.jar" should suffice, otherwise try "java -classpath coat.jar coat.ui.swing.SwingDemo".
In the toolbar, just try clicking the buttons. When using the mouse on the graphs, press Shift or Ctrl (or both) while pressing or dragging the mouse. Note: On MacOS X, it is Apple key instead of Ctrl.
For the JOGL demo, you have to reference the native libraries for your platform, using "java -classpath coat.jar:lib/jogl/jogl.jar:lib/jogl/gluegen-rt.jar -Djava.library.path=lib/jogl/jogl_native_linux coat.ui.jogl.JoglDemo".
For MacOS X and Windows, replace "native_linux" with "native_macos" and "native_windows" respectively. The MacOS X libraries are universal binaries.
In the JOGL demo, all toolbar buttons are direct click buttons (no mouse dragging).