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