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