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)(12,21)(13,23)(14,18)(15,19)(17,22)(20,24)(25,26)(27,29)(28,35)(30,34)(31,38)(32,36)(33,39)(37,40)(1,3)(2,5)(4,7)(6,8)(9,11,13,19,14,20,22,12)(10,15,17,16,18,21,23,24)(25,27,29,26)(28,31,37,33)(30,34,36,32)(35,39,40,38)(3,7)(5,8)(25,28,36,39,29,37,30,38)(26,31,34,40,27,33,32,35)(9,12,22,20,14,19,13,11)(10,16,23,15,18,24,17,21)(26,27)(31,33)(32,34)(35,40)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.