Yes you should cover a turkey when it's resting after cooking.
The resting of the turkey allows the turkey to soak of the juices that came out of it when it was baking so by allowing the turkey to rest after cooking it makes the turkey more moist and not dry.
When you cover the turkey while it's resting just cover the turkey lightly with some tin foil or aluminum foil but don't wrap it too tightly.
Always cover the resting turkey loosely and not tightly because you don't want to seal in the moisture, which will cause the skin to steam and lose whatever level of crispness the turkey has.
Then allow the turkey to rest for 30 minutes or so which will help keep the turkey from drying out and then it will be ready to serve.