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