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