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