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