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