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