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