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