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