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