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