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