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