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