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