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