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