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