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