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