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