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