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