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