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