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