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