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