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