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