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