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