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