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