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