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