St. Stephen's story is told in the Acts of the Apostles (6;7:55-60). Accused of speaking blasphemous words against the God of Moses, he was taken before the Sanhedrin. His accusers, incensed at hearing him assert that he saw "the heavens opened, and the Son of man standing on the right hand of God" (7:56), expel him from the town and stone him. Stephen is always depicted as a young man without a beard. He wears the deacon's dalmatic and stole and holds Gospels in his hands. He also carries - in his hands, balanced on his head or placed on a book - one or more stones alluding to his death.
See: Fra Angelico. Ordination of St. Stephen by St. Peter. St. Stephen Preaching.
Vittore Carpaccio. Life of St. Stephen: St. Stephen Disputing. The Ordination of St. Stephen as Deacon.
Domenico Ghirlandaio St. Stephen.
Giotto St. Stephen.
Rembrandt. The Martyrdom of St. Stephen.
The Book of Saints: The Lives of the Saints According to the Liturgical Calendar by George Angelini, Victor Hoagland (Editor). Regina Press, Malhame & Company, 1986.
365 Saints: Your Daily Guide to the Wisdom and Wonder of Their Lives by Woodeene Koenig-Brick (Author). Harper SanFrancisco, 1995.
The Golden Legend by Jacobus De Voragine, William Granger Ryan (Translator). Princeton Univ Pr, 1995.