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