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