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