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