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