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