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