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