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