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