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