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