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