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