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