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