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)(13,14,18,17)(15,19,25,24)(16,20,26,21)(22,27,28,23)(5,7,9,6)(8,11,12,10)(13,15,18,25)(14,19,17,24)(16,23,26,27)(20,22,21,28)(2,4)(5,8,9,12)(6,10,7,11)(13,16)(14,20)(15,22)(17,21)(18,26)(19,27)(23,24)(25,28)(2,4)(6,7)(10,11)(13,16)(14,21)(15,23)(17,20)(18,26)(19,28)(22,24)(25,27) involution — undirected(13,14,18,17)(15,24,25,19)(16,20,26,21)(22,23,28,27)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.