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