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