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