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