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