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