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