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