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)(11,24)(12,27)(13,29)(14,21)(15,20)(16,22)(17,26)(18,23)(19,30)(25,33)(28,34)(31,40)(32,35)(36,39)(37,38) involution — undirected(2,5)(6,8)(9,11,15,26,17,20,24,10,18,21,27,22,16,12,14,23)(13,25,31,40,33,29,38,19,34,35,39,36,32,28,30,37)(1,3,4,7)(2,6,5,8)(9,12,14,22,16,21,27,10,18,20,24,26,17,11,15,23)(13,29,30,40,32,25,39,37,34,28,38,36,33,35,31,19)(2,5)(6,8)(9,13,27,39,17,33,14,30,18,34,15,31,16,32,24,38)(10,19,11,25,22,36,20,29,23,37,21,35,26,40,12,28)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.