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