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