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