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