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)(27,33)(28,30)(29,38)(31,36)(32,37)(34,40)(35,39) 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)(26,30)(27,34)(32,38)(36,39) involution — undirected(1,3)(2,5)(4,8)(6,7)(25,27,28,34)(26,31,30,35)(29,39,37,36)(32,40,38,33)(2,6)(3,8)(9,12,14,13)(10,16,17,22)(11,19,20,21)(15,23,18,24)(25,26)(27,35)(28,30)(29,32)(31,34)(33,39)(36,40)(37,38)(2,6)(5,7)(9,13,14,12)(10,16,17,22)(11,19,20,21)(15,24,18,23)(26,30)(31,35)(32,38)(33,40)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.