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