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