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