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