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)(14,15)(18,19)(21,22,25,23)(24,27,28,26)(6,9)(10,12)(13,14,17,15)(16,19,20,18)(21,22)(23,25)(24,27)(26,28)(7,11)(10,12)(14,15)(18,19)(22,23)(26,27) involution — undirected(1,2)(3,4)(5,7,8,11)(6,10,9,12)(13,15,17,14)(16,19,20,18)(21,23,25,22)(24,27,28,26)(5,6)(7,10)(8,9)(11,12)(13,16,17,20)(14,18,15,19)(21,24,25,28)(22,26,23,27)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.