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