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