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