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