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