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