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