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