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