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