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