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