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