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)(11,19,20,16)(12,17,18,13)(21,24,23,22)(25,26,30,34)(27,31,35,38)(28,32,37,40)(29,33,39,36)(1,3,5,8)(2,6,7,4)(10,15)(12,18)(16,19)(21,23)(25,27)(26,31)(28,36)(29,32)(30,35)(33,37)(34,38)(39,40)(1,3)(2,4)(5,8)(6,7)(10,15)(11,20)(13,17)(21,23)(27,35)(28,37)(31,38)(32,40) involution — undirected(1,4)(2,3)(5,6)(7,8)(9,11,14,20)(10,16,15,19)(12,23,18,21)(13,22,17,24)(25,28)(26,32)(27,36)(29,31)(30,37)(33,35)(34,40)(38,39)(9,12,14,18)(10,17,15,13)(11,21,20,23)(16,22,19,24)(25,29)(26,33)(27,32)(28,38)(30,39)(31,37)(34,36)(35,40)(9,13,14,17)(10,18,15,12)(11,22,20,24)(16,21,19,23)(25,27)(26,31)(28,36)(29,32)(30,35)(33,37)(34,38)(39,40)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.