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