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