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