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