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