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)(11,19)(12,17)(13,18)(14,15)(16,20)(21,24)(22,23)(25,26)(27,31)(28,33)(29,37)(30,32)(34,38)(35,40)(36,39) involution — undirected(1,3,5,8)(2,6,7,4)(10,15)(11,20)(12,18)(22,24)(25,27,30,28)(26,31,32,33)(29,35,38,36)(34,39,37,40)(2,7)(4,6)(11,20)(12,18)(13,17)(16,19)(26,32)(27,28)(29,38)(39,40) involution — undirected(1,2,5,7)(3,4,8,6)(9,11,14,20)(10,16,15,19)(12,23,18,21)(13,22,17,24)(25,26)(27,33)(28,31)(29,34)(30,32)(35,40)(36,39)(37,38)(1,2)(3,6)(4,8)(5,7)(9,12,14,18)(10,17,15,13)(11,21,20,23)(16,22,19,24)(25,28,30,27)(26,33,32,31)(29,36,38,35)(34,40,37,39)(1,4,5,6)(2,8,7,3)(9,13,14,17)(10,18,15,12)(11,22,20,24)(16,21,19,23)(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.