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