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