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