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