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)(18,22)(19,23)(20,24)(25,26)(27,37)(28,40)(29,30)(31,34)(32,36)(33,39)(35,38) involution — undirected(1,2)(3,7)(4,8)(5,6)(9,11,15,12)(10,16,17,14)(13,20,22,19)(18,23,21,24)(25,27,32,39)(26,33,36,37)(28,38,31,30)(29,34,35,40)(1,3,5,4)(2,7,6,8)(10,17)(11,12)(13,22)(23,24)(25,28,32,31)(26,34,36,40)(27,38,39,30)(29,33,35,37)(9,12,15,11)(10,14,17,16)(13,20,22,19)(18,23,21,24)(25,29,32,35)(26,30,36,38)(27,34,39,40)(28,37,31,33)(9,13)(10,18)(11,19)(12,20)(14,23)(15,22)(16,24)(17,21)(25,30)(26,35)(27,28)(29,36)(31,39)(32,38)(33,40)(34,37) involution — undirected(1,4,5,3)(2,8,6,7)(9,14)(10,11)(12,17)(13,23)(15,16)(18,19)(20,21)(22,24)(25,31,32,28)(26,34,36,40)(27,30,39,38)(29,33,35,37)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.