One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,4,6)(3,5,7,8)(9,10)(11,16,24,34)(12,26)(13,18)(14,20)(15,30)(17,28)(19,21)(22,37,38,40)(23,31,29,32)(25,39,36,33)(27,35)(1,3)(2,5)(4,7)(6,8)(9,11,21,36,14,24,15,25)(10,16,19,33,20,34,30,39)(12,22,13,29,27,38,28,23)(17,31,26,37,18,32,35,40)(3,7)(5,8)(9,12,15,28,14,27,21,13)(10,17,19,26,20,18,30,35)(11,22,25,23,24,38,36,29)(16,31,33,37,34,32,39,40)(9,13,21,27,14,28,15,12)(10,18,19,35,20,17,30,26)(11,23,36,22,24,29,25,38)(16,32,33,40,34,31,39,37)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.