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