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