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