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