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