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