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