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