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