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