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