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