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