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