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