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