Next to the dipole moment property, there should be a small button to toggle viewing the dipole moment vector:
glviewer.addArrow({end: new $3Dmol.Vector3(1.0, 2.0, 3.0), color: "black", wireframe: false});
The components are in pm7: dipole (the pm7 will change with the calculation method)
"dipole": [
"-0.001",
"-0.001",
"-0.074"
],