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