One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,4,5)(3,6,7,8)(9,10,14,17)(11,18,21,15)(12,16,13,22)(19,24,20,23)(9,11)(10,15)(12,19)(13,20)(14,21)(16,23)(17,18)(22,24)(26,30)(27,34)(28,31)(32,35)(33,38)(36,39) involution — undirected(2,5)(6,8)(9,12,14,13)(10,16,17,22)(11,19,21,20)(15,23,18,24)(25,26,31,38,29,33,28,30)(27,35,39,37,36,32,34,40)(9,13,14,12)(10,16,17,22)(11,20,21,19)(15,23,18,24)(27,36)(32,35)(34,39)(37,40)(1,3,4,7)(2,6,5,8)(11,21)(15,18)(19,20)(23,24)(25,27,31,39,29,36,28,34)(26,32,38,40,33,35,30,37)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.