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