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