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