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