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