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