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