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