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