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