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