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