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)(12,16)(13,18)(14,17)(15,21)(20,22)(23,24)(25,26)(27,30)(28,33)(29,34)(31,36)(32,38)(35,39)(37,40) involution — undirected(1,2)(3,7)(4,5)(6,8)(9,11,14,21)(10,15,17,19)(12,20,18,24)(13,22,16,23)(25,27,30,26)(28,33,36,31)(29,32,38,34)(35,39,37,40)(2,5)(3,8)(9,12,14,18)(10,16,17,13)(11,20,21,24)(15,23,19,22)(25,28,30,36)(26,31,27,33)(29,37,38,35)(32,40,34,39)(1,3,4,8)(2,6,5,7)(10,17)(12,18)(15,19)(20,24)(25,29,30,38)(26,32,27,34)(28,35,36,37)(31,39,33,40)(2,5)(6,7)(11,21)(15,19)(20,24)(22,23)(26,27)(31,33)(32,34)(39,40) involution — undirected(9,13,14,16)(10,18,17,12)(11,22,21,23)(15,24,19,20)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.