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