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