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