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