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