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