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