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