I did a search for quilting with monopoly on a baby quilt and got this hit: Don't know if this is an opinion or based on some other info. I use so fine a lot and when I have a bunch of different colors, I just start by tossing thread from each color I am considering and seeing which blends in with most of the colors. If there is a background color and it is light, I tend to stick with a lighter color but on a white background I have used pale yellow, blue, green, or pink and as so fine is so fine, the thread doesn't show that much.
Monofilament threads because they are hard to see should be avoided on baby quilts. If by chance your stitches come loose they could wrap around babies fingers and toes and cut off circulation.