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)(25,26,29,30)(27,33,34,31)(28,36,38,32)(35,39,37,40)(5,6,7,8)(10,14)(11,17)(16,21)(18,23)(26,30)(27,34)(32,36)(35,37)(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)(33,34)(35,39)(36,38)(37,40) involution — undirected(1,2)(3,4)(9,11)(10,15)(12,18)(13,17)(14,20)(16,22)(19,23)(21,24)(25,27,29,34)(26,31,30,33)(28,37,38,35)(32,40,36,39)(9,12,13,19)(10,16,14,21)(11,18,17,23)(15,22,20,24)(25,28)(26,32)(27,35)(29,38)(30,36)(31,39)(33,40)(34,37)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.