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