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