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