It probably doesn't exist. The riff is not terribly complicated though. I was lucky enough to play and sing the song many times with the guy who invented the riff, James Burton. I recorded him playing it with me, and practiced it over and over. Never got it exactly right, but close.
Love to hear it if you can find one.
Marvelous guitar player, enjoyed his work with Elvis and on the Wildlife Concert with John Denver. Lucky you Don!