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