The Cathedral Rock group is formed into three basic mesas (plus outrigger spires and the like), North, Middle, and South. This would be the South one.
Getting There
Hike up to Cathedral Rock to the notch where you can see an unusual volcanic plug (some say this is the vortex). Follow the trail over the notch and keeping to the left side of the rock. Head in between 2 sandstone formation and follow the rock heading south. Come around the formation to head to the west and start looking for bolts on the south facing face.
The Classics
Mountain Project's determination of some of the classic, most popular, highest rated routes for South Mesa:
"Vortex in a Can" is located on the south face of the South Mesa of the Cathedral rock group. The recommended approach is the same as for the Mace but cont to contour around the east side to the south/southwest. It's quite a ways though, a quicker more direct approach might be found directly up from Verde School road from Oak Creek Villiage.
Agree with Mark that the Verde Road might be quicker, although you may get shot at hiking through the million dollar lots. The two best options:
1: Follow Aimee's directions from the saddle. When you hike around to the Southwest, you'll pass two routes on the way to Vortex. Roker and New Age Rage. Contour around the shoulder to the left just pass these routes (descriptions forthcoming!) and hike for about 5 minutes. Look up to the left for the descibed bolts. Vortex is just to the left of Freedom, the beautiful 11C dihedral.
2: The other option is to head left at the saddle, cut through the corridor on your left, and drop down on the back-side of the mace. From here, contour to your right, all the way around the South end of Catherdral, and back to the west. Takes about 15 min. from the saddle. Make sure to keep your eyes peeled for some sweet old aid lines along the way!