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