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