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