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)(13,14,18,19)(15,17,16,20)(21,22)(23,25)(24,26)(27,28)(6,9)(7,12)(14,19)(17,20)(22,24)(25,27) involution — undirected(5,7)(6,10)(8,12)(9,11)(13,15,18,16)(14,17,19,20)(21,23,26,28)(22,27,24,25)(1,2)(3,4)(5,7)(6,10)(8,12)(9,11)(13,16,18,15)(14,20,19,17)(21,24,26,22)(23,25,28,27)(5,6)(7,10)(8,9)(11,12)(13,17,18,20)(14,15,19,16)(21,25)(22,23)(24,28)(26,27)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.