The map below is the best approximation I could make from the limited information. It is comprised primarily of the Baronies of Tirerrill and Boyle. The southern boundary with Corcu Achlainn is soft and uses natural topographical features such as rivers, etc., but it should be close enough. The southwestern boundary may extend a little too near Ráth Crúachán, but again, it should be a reasonably close approximation because Elphin was definitely in the original territory.
Beaucoup thanks to the
Irish Townlands website.