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