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