Though he is a modern greek artist, Vlasios Tsotsonis works in a very traditional style that is absolutely lovely. Unfortunately, in none of his work so far does there seem to be any depictions of St. Lydia. His mosaics in the Baptistery are very beautiful, and give a good idea of what the inside of the church is like.
The pictures included in this post are of the inside of the central dome in the church. The main scene is of Christ's Baptism. A detail shot of the angels attending his baptism is included. It is followed by a picture of Angels over the Jordan River , and a detail shot of a mermaid/angel like figure in the water.
Mosaics:
Photo Credits: http://vlasiostsotsonis.com/main.php
http://www.rose-publishing.com/Travel/Travel.html