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