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