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