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