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