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