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