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