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)(15,21,17,19)(16,24)(18,22)(20,26)(23,28,25,27)(1,2)(3,4)(6,10)(7,8)(11,12)(13,15)(14,19)(16,23)(17,18)(20,27)(21,22)(24,28)(25,26) involution — undirected(2,4)(13,16)(14,20)(15,23)(17,25)(18,26)(19,27)(21,28)(22,24) involution — undirected(5,7)(6,11)(8,9)(13,17,18,15)(14,21,22,19)(16,25,26,23)(20,28,24,27)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.