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