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