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