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