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