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