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