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