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