Kath pointed out a sealion beastie from 1st ed monster manual, and there are so many black and white illustrations that are downloadable and suitable for coloring. https://www.google.com/search?client=ms-android-verizon&tbm=isch&q=monster+manual+pictures&chips=q:monster+manual+pictures,g_2:1st&sa=X&ved=0ahUKEwiI7cW4h_vXAhWiSN8KHXqnBJ4Q4lYIOSgA&biw=360&bih=560&dpr=3 Even in a GIMP or another bit of public domain computer software, it can be very comforting as coloring book fodder. DAT or erol otus stuff works well, too.