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