One vertex per element, one color per generator, with an edge from x to x·s.
(1,2) involution — undirected(3,4)(5,7)(6,9)(8,10)(11,12,15,20,16,19,28,35)(13,21,23,36,24,17,29,31)(14,18,26,34,27,33,39,42)(22,32,37,41,25,30,38,40)(4,7)(5,10)(8,9)(11,13,16,24)(12,17,19,21)(14,25,27,22)(15,23,28,29)(18,32,33,30)(20,36,35,31)(26,38,39,37)(34,40,42,41)(11,14,16,27)(12,18,19,33)(13,22,24,25)(15,26,28,39)(17,30,21,32)(20,34,35,42)(23,37,29,38)(31,40,36,41)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.