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