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