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