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