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)(23,27)(24,25)(26,28) involution — undirected(5,6,9,7)(8,11,12,10)(13,14)(15,19)(16,20)(17,18)(22,24)(26,27)(6,7)(8,12)(14,18)(16,19)(21,23,25,28)(22,26,24,27)(1,2)(3,4)(5,7,9,6)(8,10,12,11)(13,15)(14,19)(16,18)(17,20)(21,23)(22,26)(24,27)(25,28)(5,8)(6,10)(7,11)(9,12)(13,16,17,19)(14,20,18,15)(21,24,25,22)(23,26,28,27)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.