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