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