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