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