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