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