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)(13,14,19,21,18,23,16,26)(15,20,24,27,25,17,22,28)(5,7)(6,9)(8,12)(10,11)(13,15)(14,20)(16,22)(17,23)(18,25)(19,24)(21,27)(26,28) involution — undirected(1,2,3,4)(6,10)(9,11)(13,16,18,19)(14,21,23,26)(15,24,25,22)(17,27,20,28)(7,12)(9,11)(15,25)(17,20)(22,24)(27,28) involution — undirected(6,10)(9,11)(13,17,19,28,18,20,16,27)(14,22,21,15,23,24,26,25)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.