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