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