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