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