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