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