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