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