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