Yes you can grind coffee beans in a Vitamix machine.
To grind your coffee beans coarsely in the Vitamix Machine just attach the dry grains container to the Vitamix machine and add the coffee beans.
Then on the Vitamix machine select Variable Speed 1 and then turn the Vitamix machine on slowly, increasing the speed to Variable 8.
Then allow the coffee beans to grind in the Vitamix machine for 10 seconds and then the coffee beans should be fully ground down.
You can also make brewed iced coffee in your Vitamix from those ground coffee beans.
A Vitamix machine is a pretty versatile machine and can be used for a variety of things including coffee beans.
However a coffee grinder does much better.