I cooked my farro in a rice cooker for about 45 minutes on the brown rice setting. 3 cups water to 1 cup farro. You can also cook it on the stove for 40 minutes to an hour until the farro is tender and chewy. (Check it every now and then to make sure it's not burning to the bottom of the pan). Soak farro overnight to speed up your cook time. Make a big batch and store leftovers in the fridge for salads throughout the week.
Make ahead tips: everything can be made and stored in the fridge up to 2 days in advance. For best texture, I would suggest adding the lighter salad greens at the last minute and roasting the sweet potatoes just before you're ready to serve.