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