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