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