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