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