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