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