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