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