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