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