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