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