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