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