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