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