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