I looked at the panel and it would be fun to work with. Lucky for you they are spaced enough between that you can cut apart, and sew together without losing any of the paintings!
It might be as simple as following the same idea as they have ... frame each up with a black border, and join them in a similar layout as what they have used. Another idea ... 1/2" black border then 1/4" flange to pop the colours of the painting, then a larger black border. Each flange could be a different colour. Then randomly place the paintings, as though they are art on the wall.
I'm dealing with a similar challenge right now for a totally different quilt .... my plan is to measure the blocks (your paintings) and then start drafting possibilities out on graph paper.