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