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