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