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