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