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