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