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