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