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