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