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