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