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