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