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