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