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