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