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