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