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