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