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