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