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