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