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