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