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