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