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