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