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