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