An integral part of holding family devotions is reading from the Bible. Obviously, anything with a lot of words and more than a few pages will present a challenge for most little ones. There is a way to train up a young child for listening to readings from the Bible as part of the family circle, and I certainly encourage that kind of instruction. However, I recognize that few families operate under that level of teaching. Most parents function within the parameter of what-can-I-do-right-now-that’ll-work-so-I-can-get-this-devotional-thing-off-the-ground mindset.
One impressive resource I've found is The Big Picture Story Bible by David Helm. This is not a light book; there’s over 400 pages in it. But the book provides a very good overview of the Bible from Old Testament to New, telling the story of God and His Son Jesus in language designed for little ones to understand. There are only a few sentences per page and the illustrations will give you plenty to talk about as you engage your child in the text and its meaning.