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