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)(11,17,19,15)(12,16,22,20)(18,24,21,23)(25,26)(27,35)(28,29)(30,32)(31,34)(33,39)(36,37)(38,40)(1,3,4,8)(2,5,6,7)(9,10,13,14)(11,15,19,17)(12,16,22,20)(18,23,21,24)(25,27,31,30)(26,32,34,35)(28,38,33,36)(29,37,39,40)(1,3)(2,5)(4,8)(6,7)(10,14)(15,17)(16,20)(23,24)(25,27,31,30)(26,32,34,35)(28,38,33,36)(29,37,39,40)(1,3)(2,5)(4,8)(6,7)(9,10)(11,15)(12,20)(13,14)(16,22)(17,19)(18,24)(21,23)(25,28,31,33)(26,29,34,39)(27,36,30,38)(32,40,35,37)(1,2)(3,5)(4,6)(7,8)(9,11,13,19)(10,15,14,17)(12,21,22,18)(16,24,20,23)(25,29)(26,33)(27,37)(28,34)(30,40)(31,39)(32,36)(35,38)(9,12,13,22)(10,16,14,20)(11,18,19,21)(15,23,17,24)(25,30,31,27)(26,32,34,35)(28,36,33,38)(29,37,39,40)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.