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