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