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