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