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