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