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