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