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