If you know someone who has an overhead projector, you can tape paper to the wall, enlarge the image and trace it onto the paper on the wall. I just did something like this for a friend who needed a large anchor pattern for applique. The only way I know to attach it to the quilt after quilting would be to do needle turn by hand and only go thru the backing (or backing and batting).
If you don't find a better solution and would like me to try, I would be glad to send you something. I am not sure I can get it as large as 40" but could try it and let you know.