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