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