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