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