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