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