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