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