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