My suggestion is not to tell them stories but have them tell you stories.
You could go around the room and ask each student to say a sentence in the
story so the story grows as it goes around the room. I think small kids
are more interested in the picture than facts about the artists' lives.
You can ask guided questions that help the kids to discover the answers.
While they look for answers, they are actively engaged in the picture
rather than passively "watching." Its the difference between looking and
seeing. Start by asking them what is in the picture and procede to asking
about connections and meanings. Ask why the artist did it this way or that
Try to select visuals that have a lot going on in them (busy pictures) that
lend themselves to discovery by careful viewing. Try to use big visuals
(slidess or color transparencies which work on an overhead can be made from
posters--check with a local quick printer or graphics shop) so everyone can
see the details well.
The Surgeon's Motto: "Never say 'oops!', always say 'there!'