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