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