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