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