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