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