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