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