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