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