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