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