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