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