One vertex per element, one color per generator, with an edge from x to x·s.
(2,7)(3,8)(4,5)(9,10)(11,17)(12,20)(13,16)(14,18)(15,22)(19,24)(21,23)(25,26,30,34)(27,35,38,39)(28,33,29,32)(31,37,40,36)(1,2,6,3)(4,8,5,7)(9,11,13,19)(10,14,16,23)(12,21,22,18)(15,24,20,17)(25,27,30,38)(26,31,34,40)(28,37,29,36)(32,39,33,35)(1,3,6,2)(4,8,5,7)(14,23)(17,24)(27,36)(28,29)(31,35)(32,33)(37,38)(39,40)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.