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