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