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