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