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